The present invention relates to an alarm method and device against inappropriate actuation of an aircraft rudder bar by a pilot during directional control of the aircraft.
It is known that directional control of an aircraft is mainly ensured by an articulated rudder, able to rotate in two opposite directions of rotation between an aerodynamically neutral position and a stopped position of maximum rotation. To this end, the rudder is controlled by a mobile control facility (rudder bar) available to the aircraft pilot. This facility is generally equipped with two pedals, the respective depression of which causes the facility to travel in two opposite directions, associated, respectively, with the two opposite directions of rotation of the rudder. In particular, this rudder bar controls the rotation of the rudder in such a way that the amplitude of the rotation of said rudder depends on the amplitude of the rudder bar travel. Consequently, a depression of the right pedal, for example, conveys the wish of the pilot to cause a yawing moment tending to move the nose of the aircraft to the right, this moment being obtained by a deflection of the rudder to the right. Thus, in a few special cases, the pilot can act on the rudder bar with the aim of modulating the aerodynamic forces being applied to the aircraft, so as to modify or control the lateral path. These special cases are limited, like the control of engine failure and the alignment maneuver, to situations during a crosswind landing.
Nevertheless, this steering facility being available to the pilot in all the phases of flight, it can occur that, in especially dynamic and unusual situations, the pilot actuates the rudder bar in a wholly inappropriate manner. This inappropriate actuation, in these phases of flight, can potentially generate excessive loads on the vertical stabilizer.
Furthermore, to protect the aircraft, when the speed of the aircraft exceeds a speed threshold, it is possible to limit the rudder rotation in a manner inversely proportional to the speed of the aircraft, i.e. to make the rudder's TLU (Travel Limiter Unit) stop dependent on the speed of the aircraft, with the aim of limiting the stresses to which said aircraft is subjected at high speeds and, thus, of enabling the performance of yaw maneuvers, including at high speed.
It can however occur, even with the travel limiter device, that actuation of the rudder bar inversely coordinated with the position of the rudder be such that the aircraft can experience excessive loads on the vertical stabilizer.
The present invention has the object of preventing such a risk to the aircraft during directional control of the aircraft. It concerns an alarm method making it possible to alert a pilot to an inappropriate actuation of the aircraft rudder bar.